OSI Layer
7. Application
6. Presentation
5. Session
- Above 3 layers can be grouped as one. Emits data such as HTTP, etc
- PDU (Protocol data unit): Data
4. Transport
- PDU: Segment
- Contains Port Addresses to route to services and application (port 4500, etc)
- TCP/UDP
3. Network
- PDU: Packet
- IP (IPv4 / IPv6)
- Contains addresses in terms of IP Addresses
2. Data link
- PDU: Frame
- Physical network card. Has MAC addresses
1. Physical
- Layer where data flows (optical, etc)
TCP/IP
- Application layer
- Transport layer
- Inter-network layer
- Network Access
Types of load balancer
- Application load balancer (L7) Working with the application layer protocols such as HTTP. Routes HTTP requests based on path, http method, headers, cookies, etc. Example: Nginx (reverse proxy), AWS ALB
- Network load balancer (L4) Works at network layer, routes TCP/UDP packets. Routes based on IP addresses. Example: AWS NLB